/Engine/Source/Runtime/Engine/Classes/Components/ActorComponent.h
ReadyForReplication gets called on replicated components when their owning actor is officially ready for replication. Called after InitializeComponent but before BeginPlay. From there it will only be set false when the component is destroyed. This is where you want to register your replicated subobjects if you already possess some. A component can get replicated beforeHasBegunPlay()is true if inside a tick or inBeginPlay()an RPC is called on it. Requires component to be registered, initialized and set to replicate.
virtual void ReadyForReplication()